The directive would govern electronics larger than a cellphone, CNN reported, including laptops, tablets, e-readers, SLR cameras and video game players. It was allegedly made in response to an unspecified security threat, Reuters reported. U.S. officials learned of the threat several weeks ago and had been mulling imposing the security measures. They were expected to be announced as early as Monday evening.

The rule would come from the Department of Homeland Security and would cover a dozen airlines flying from about as many countries, including U.S. allies Saudi Arabia and Jordan. An aviation official told CNN that the countries included were targeted due to security screening procedures before nonstop flights to the U.S., and flights that had a layover in a country before arriving on American soil would likely be exempt if that country had stricter security checks.

Earlier Monday, Royal Jordanian Airlines tweeted that “following instructions from the concerned U.S. departments,” “carrying any electronic or electrical device on board the flight cabins is strictly prohibited.” Cell phones and medical devices needed while in-flight were excluded from the ban, the airline said.

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The tweet was later deleted without explanation, but the company told CNN that “further updates will be announced soon.” Forbes reported that airlines have 96 hours to comply with the new regulations.

American airlines are not impacted, a source told CNN, because no U.S.-based airline flies directly from one of the 12 countries to the U.S. The regulation would reportedly be enacted for a limited time frame.